Wearable Activity Monitors and Weight Loss

It may be fun to record how many steps you took today. But does wearing an activity monitor help a person to lose weight?

To find out, researchers at The University of Pittsburgh enlisted nearly 500 people in a randomized trial. For six months, all participants were asked to adhere to a low-calorie diet and to exercise in prescribed ways. After six months the diet and exercise recommendations were continued for another year and a half, but now half of the participants wore an activity monitor and the other half (the control group) did not.

The researchers had hypothesized that those wearing the activity monitors would lose more weight than those in the control group. Surprisingly, that was not the case. In fact, the activity monitor-wearers lost slightly less weight; only 7.7 lb versus 13.0 lb. in the control group.

So what are we to make of this? Not much, except that human beings and their behaviors are, well, complicated. Perhaps wearing an activity monitor reduces diet compliance (self-reported in this study). Or perhaps an activity monitor gives the wearer an inflated perception of how hard they actually are exercising, so that they aren't expending as many calories as they think (physical activity, too, was self-reported). Who knows? For now, all we know is that wearing an activity monitor doesn't help one lose weight.